Concrete compositions are produced by blending cement, water, fine aggregate and coarse aggregate together and, among cement compositions, they give curing products superior in strength and durability as compared with pastes and mortars. Therefore, they are widely and adequately used in such applications as outer walls of buildings and building structures. In such concrete compositions, a reduced water content per unit volume of concrete leads to improvements in performance of curing products. In the present concrete industry, improvements in strength and durability of concrete structures are strongly demanded and, therefore, to reduce the unit water content has become an important task.
Generally, an admixture for increasing the air entrainment and permeability is added to such concrete compositions. The task of such admixture in concrete compositions is to exhibit its dispersing ability sufficiently so that the permeability and workability of concrete compositions can be secured even when the unit water content is reduced for realizing improvements in strength and durability and, at the same time, retain its dispersing ability stably even with the lapse of time to provide good concrete compositions. Recently, the importance of such an admixture has been duly recognized and technological innovations have been made actively. In particular, a large number of polycarboxylic acid dispersants have been investigated since they exhibit a higher level of water reducing performance as compared with the conventional naphthalene-based ones and the like. The use of such a dispersant results in increased air entrainment and increased bubble size. Thus, the combined use thereof with an air entraining agent (AE agent) is in general practice for entraining fine and good-quality bubbles and thereby improving the freeze-thaw durability.
However, a drawback of the combined use of a polycarboxylic acid dispersant and an AE agent is that the amount of air entrained gradually increases with the continued kneading of concrete and, therefore, it becomes difficult to attain a desired level of concrete strength. Although it is possible to reduce the amount of air entrained temporarily using an defoaming agent known in the prior art, the continued kneading results in an increased amount of air entrained. Further, from the in-situ workability viewpoint, it is difficult to add an defoaming agent just before concrete placing; it is demanded that the addition of an defoaming agent be made in the step of preparing concrete. In cases where the addition of an AE agent is essential as a measure against freezing and thawing or where kneading is carried out for a long period of time during transportation, in particular, the increase in amount of air entrained becomes a serious problem.
Meanwhile, the addition of alkylene oxide adducts derived from specific compounds to concrete compositions or the like has been investigated.
As regards cement dispersants which comprise, as an essential constituent, a polyether polyol or polyether polyol derivative having a molecular length of 6,000 to 2,000,000 as resulting from addition, to an amine compound, of 20 to 300 moles, per active hydrogen atom of the amine compound, of alkylene oxides comprising ethylene oxide and propylene oxide as essential ones, cement dispersants have been disclosed which comprise, as an essential constituent, an adduct resulting from addition of ethylene oxide and propylene oxide, optionally together with styrene oxide, to polyethyleneimine, ethylenediamine or diethylenetriamine (cf. e.g. Patent Document 1: Japanese Kokai Publication Sho60-27638, pages 1 and 3).
As regards mixtures comprising a polycarboxylic acid salt liquefying agent for inorganic building materials, such as cement, and a butoxylated polyalkylenepolyamine or a salt thereof to be used for deaeration, there have been disclosed butoxylated polyalkylenepolyamines or polyethyleneimine-butylene oxide adducts as salts thereof (cf. e.g. Patent Document 2: Pamphlet of International Patent Application WO 00/17128, pages 1, 17 and 18).
As regards a method of adjusting the amount of air entrained which method comprises using an ethylene oxide derivative (I) of a primary amine and a water-soluble polycarboxylic acid polymer (II) in a specified weight ratio in kneading cement mortar or concrete, laurylamine-ethylene oxide adducts have been disclosed as the primary amine-derived ethylene oxide derivative (I) (cf. e.g. Patent Document 3: Japanese Kokai publication Sho63-11557, pages 1, 2 and 5).
As regards hydraulic compositions which comprise (a) a water-soluble polymer comprising a polyalkylene oxide derivative resulting from addition of 10 to 1,000 moles of an alkylene oxide to a monohydric alcohol, monohydric mercaptan, alkylphenol, amine or carboxylic acid containing 6 to 30 carbon atoms within the molecule, (b) a high-performance plasticizer, and (c) a hydraulic powder, there have been disclosed ethylene oxide adducts derived from mixtures of stearyl alcohol and cetanol, ethylene oxide and propylene oxide adducts derived from nonylphenol, ethylene oxide adducts derived from dodecylmercaptan, ethylene oxide adducts derived from palmityl alcohol, ethylene oxide adducts derived from dodecylamine, and ethylene oxide adducts derived from lauric acid, among others (cf. e.g. Patent Document 4: Japanese Kokai Publication Hei08-73250, pages 1, 2, 7 and 8).
In these technologies, however, no sufficient investigations have been made concerning how to stably maintain the amount of air entrained in concrete compositions. There is thus room for contrivance for designing the structures of alkylene oxide adducts so that they can exhibit excellent performance and give concrete compositions showing good performance excellent in strength and durability.
Further, cement admixtures comprising, as an essential constituent, a copolymer obtained by copolymerization of a monomer composition comprising (a) an oxyalkylene group-containing monomer having a specified structure and (b) an unsaturated carboxylic acid monomer and/or a salt of such copolymer have been disclosed, and the use of alkoxypolyalkylene glycols obtained by addition of an alkylene oxide containing 2 to 4 carbon atoms to an aliphatic or alicyclic alcohol having an alkyl group containing 4 or 5 carbon atoms, and a (meth)acrylic acid ester compound (cf. e.g. Patent Document 5: Japanese Kokoku Publication No. 2997243, pages 1, 5).
Cement admixtures comprising, as an essential constituent, a first copolymer obtained by copolymerization of two oxyalkylene group-containing monomers (a) and (b) each having a specified structure and not more than 50% by mass (% by mass based on the total amount of monomer constituents) of (c) an unsaturated carboxylic acid monomer and/or a salt of such copolymer have been disclosed and, thus, (meth)acrylate ester compounds have been disclosed which are derived from alkoxypolyalkylene glycols obtained by addition of an alkylene oxide containing 2 to 4 carbon atoms to an aliphatic or alicyclic alcohol having an alkyl group containing 4 to 30 carbon atoms have been disclosed as the monomer (a) and a monomer (b) whose terminal oxyalkylene group ends in an alkyl group smaller in number of carbon atoms than in the terminal oxyalkylene group of the monomer (a) or in a hydrogen atom (cf. e.g. Patent Document 6: Japanese Kokoku Publication No. 2992511, pages 1,2,4 and 5).
Cement admixtures comprising, as an essential constituent, a copolymer obtained by polymerizing (a) a polyalkylene glycol monoester monomer having a specified structure and (b) at least one monomer selected from among acrylic monomers and unsaturated dicarboxylic acid monomers or a salt of such polymer and, thus, there have been disclosed ester compounds derived from alkoxypolyalkylene glycols obtained by addition of an alkylene oxide containing 2 or 3 carbon atoms to alcohols containing 6 to 30 carbon atoms as the polyalkylene glycol monoester monomer (a) and (meth)acrylic acid (cf. e.g. Patent Document 7: Japanese Kokai Publication Hei11-60303, pages 1, 2 and 3). Further, cement admixtures have been disclosed which comprise, as an essential constituent, a copolymer comprising, as essential constituents, (a) a polyalkylene glycol monomer having a specified structure, (b) a polyalkylene glycol monoester monomer having a terminal hydrocarbon group containing a smaller number of carbon atoms than the number of carbon atoms in the terminal group of the polyoxyalkylene group in monomer (a) and at least one monomer (c) selected from among acrylic monomers and unsaturated dicarboxylic acid monomers, or a salt of such copolymer, and (meth)acrylic acid ester compounds with alkoxypolyalkylene glycols obtained by addition of an alkylene oxide containing 2 or 3 carbon atoms to alcohols containing 6 to 30 carbon atoms and having a benzene ring have been disclosed as the polyalkylene glycol monomer (a) (cf. e.g. Patent Document 8: Japanese Kokai Publication Hei11-60304, pages 1, 2 and 5).
As regards concrete admixtures comprising, as a main component, a copolymer composed of (a) an unsaturated bond-containing polyalkylene glycol monoester monomer having a specified structure and (b) a monomer copolymerizable with the monomer (a), esterification products from a polyalkylene glycol adduct of alcohol containing 6 to 18 carbon atoms and (meth)acrylic acid (cf. e.g. Patent Document 9: Japanese Kokai Publication Hei09-241056, pages 1, 2 and 3) and alkylphenoxypolyethylene glycol monoesters and alkylphenoxypolypropylene glycol monoesters (c.f. e.g. Patent Document 10: Japanese Kokai Publication H09-241057, pages 1, 2 and 3) have been disclosed as the polyalkylene glycol monoester monomer (a).
Dispersants for powder-water system slurries which comprise a copolymer (A) composed of (a) an α,β-unsaturated carboxylic acid (salt), (b) a C6-30 monoolethylene oxide (15–50 moles) adduct (meth)acrylate and (c) a hydrophobic unsaturated monomer, if necessary together with (d) another copolymerizable monomer (cf. e.g. Patent Document 11: Japanese Kokai Publication Hei08-53522, pages 1 and 2) and shrinkage-reducing dispersing agent for use in cementitious composition which comprise a graft polymer resulting from chemical binding of oligoalkylene glycols and/or polyhydric alcohols to side chains of a polycarboxylic acid or a salt thereof or which comprise a graft polymer resulting from chemical binding of oligoalkylene glycols and/or polyhydric alcohols and a polyalkylene glycol or a derivative thereof to side chains of a polycarboxylic acid or a salt thereof have been disclosed (c.f. e.g. Patent Document 12: Japanese Kokai Publication Hei08-268741, pages 1 and 2).
In these technologies, however, no sufficient investigations have been made concerning how to improve the freeze-thaw durability or stably maintain the amount of air entrained in concrete compositions. Thus, there is room for contrivance for designing more adequate alkylene oxide adduct structures to thereby provide concrete compositions capable of exhibiting good performance in these respects and with respect to strength and durability, or room for investigation for enabling concrete compositions to show sufficient levels of permeability even when the amount of water relative to cement is further reduced.
Further, an agent for improving the surface appearance of cement moldings which comprises a polyalkylene glycol derivative(s) composed of a polyethylene glycol-polypropylene oxide adduct and/or an ethylenediamine-polyethylene oxide adduct-polypropylene oxide adduct (cf. e.g. Patent Document 13: Japanese Kokai Publication Hei11-199290, pages 1 and 2) and a cement additive composition comprising a mixture, in a specified ratio, of a polycarboxylic acid compound and a nitrogen-containing polyoxyalkylene compound having a specific structure (cf. e.g. Patent Document 14: Japanese Kokai Publication Hei07-232945, pages 1 and 2) have been disclosed. In these technologies, however, no investigation has been made concerning the case of an AE agent being used. Thus, there is room for contrivance for providing concrete compositions capable of exhibiting excellent performance even when an AE agent is used and, at the same time, capable of providing good strength and durability characteristics.
Furthermore, an admixture for use in cementitious compositions which comprises a water-soluble air-controlling agents and a dispersant each for cement compositions (cf. e.g. Patent Document 15: pamphlet of International Patent Application WO 01/42161 A2, pages 1 and 28) and an admixture for cementitious compositions which comprises a water-insoluble defoaming agent and a dispersant each for cement compositions, together with a dissolving agent for the water-insoluble defoaming agent (cf. e.g. Patent Document 16: pamphlet of International Patent Application WO 01/42162 A1, pages 1 and 24) have been disclosed. As regards these admixtures for cementitious compositions, however, there is room for investigation concerning how to enable them to exhibit good strength and durability performance by designing the structure of each defoaming agent.